NullPointerException in ChatActivity.onPrepareOptionsMenu when currentConversation is not yet loaded

Summary

ChatActivity crashes with NullPointerException in onPrepareOptionsMenu when the menu is prepared before currentConversation is fully loaded. The crash is reliably reproducible on master by opening any conversation in an automated test environment (instrumented test, faster than human navigation).

Reproduction

1. Build current master (tested at HEAD 5aeace618 bump version to 23.0.0).
2. Launch ChatActivity programmatically (e.g. from an instrumented test, or by navigating from the conversation list very quickly).
3. The activity crashes before fully rendering.

Stack trace

java.lang.NullPointerException
    at com.nextcloud.talk.chat.ChatActivity.onPrepareOptionsMenu(ChatActivity.kt:2731)
    at android.app.Activity.onPreparePanel(Activity.java:4480)
    at androidx.activity.ComponentActivity.onPreparePanel(ComponentActivity.kt:464)
    at androidx.appcompat.view.WindowCallbackWrapper.onPreparePanel(WindowCallbackWrapper.java:99)
    at androidx.appcompat.app.AppCompatDelegateImpl$AppCompatWindowCallback.onPreparePanel(...)
    at androidx.appcompat.app.ToolbarActionBar.populateOptionsMenu(ToolbarActionBar.java:459)
    at androidx.appcompat.app.ToolbarActionBar$1.run(ToolbarActionBar.java:58)

Root cause

ChatActivity.kt:2731 uses a non-null assertion on currentConversation:

searchItem.isVisible =
    hasSpreedFeatureCapability(spreedCapabilities, SpreedFeatures.UNIFIED_SEARCH) &&
    currentConversation!!.remoteServer.isNullOrEmpty() &&  // ← !! crashes when currentConversation is null
    !isChatThread()

onPrepareOptionsMenu is called by the system as soon as the toolbar is drawn, but the conversation is loaded asynchronously. Under fast/automated navigation, the menu is prepared before currentConversation is set.

Suggested fix

Either guard the whole block with currentConversation?.let { ... }, or use safe-call on the field:

searchItem.isVisible =
    hasSpreedFeatureCapability(spreedCapabilities, SpreedFeatures.UNIFIED_SEARCH) &&
    (currentConversation?.remoteServer?.isNullOrEmpty() ?: true) &&
    !isChatThread()

(Several other currentConversation?.… calls already exist in the same method, suggesting this !! is an oversight rather than an invariant.)

Suspected commit

Likely introduced by 96b4f4308 New chat architecture + replace ChatKit with Compose + chat relay via signaling, which restructured ChatActivity.

Environment

• talk-android master @ 5aeace618
• Android 13 / API 33 emulator (Pixel 3a, headless)
• Reproduced via instrumented androidx.test UI navigation

Start in ChatActivity.kt at onPrepareOptionsMenu, especially line 2731, and inspect the existing nullable currentConversation handling nearby. Reproduce the issue with the described instrumented navigation or automated test setup. Done means opening ChatActivity while the conversation is still loading no longer throws a NullPointerException and the unified-search menu visibility remains correct.